Improvement in deuterium recovery from water–isotope mixture by thermal diffusion in the device of branch columns

•Recovery of deuterium by thermal diffusion from water–isotope mixture has been investigated.•The undesirable remixing effect can be reduced by employing the device of branch columns.•Deuterium recoveries were compared with that in a single column of the same total column length.•Considerable recovery improvement is obtainable in the device of branch columns, instead of in a single-column device. Deuterium recovery from water–isotopes mixture using thermal diffusion can be improved by employing the branch column device, instead of single column devices, with the same total column length. The remixing effect due to convection currents in a thermal diffusion column for heavy water enrichment is thus reduced and separation improvement increases when the flow rate or the total column length increases. The improvement in separation can reach about 50% for the numerical example given.